Matrix multiple gun assembly for cathode ray tube



y 10, 1966 J. H. JOHNSON 3,250,935

MATRIX MULTIPLE GUN ASSEMBLY FOR CATHODE RAY TUBE Filed Aug. 4, 1964 INVENTOR dkyfl Jllraavrg ATTORNEYS United States Patent tucky Filed Aug. 4, 1964, Ser. No. 387,321 7 Claims. (Cl. 31370) This invention relates to electron guns and more particularly it relates to multiple gun assemblies providing a converged single beam, such as used in color television tubes.

In the prior art multiple gun assemblies for cathode ray tubes have been assembled from a plurality of single guns held together loosely by an array of brackets or clamps. The U.S. Patent 3,134,923 to Brown issued May 26, 1964, is an example of such assembly techniques. Thus, during assembly of the multiple-gun structure, not only is therea considerable chance for variation in spacings and resulting operation between one gun and the next, but the various parts may be subjected to mechanical and thermal stresses during and after assembly which produce erratic operation.

It is Well known that the balance of operational characteristics between all the guns in a color tube is required to maintain a proper color representation. Thus, a construction which permits even small possibilities in misalignment or tedious and precise assembly techniques which can lead to error favor a high reject rate in finished tubes, which are costly.

Therefore, it is an object of this invention to provide an improved multiple-gun assembly.

Another object of the invention is to provide a multiple-gun assembly which provides a fixed spacing of the various parts in an optimum relationship.

Therefore, in accordance with this invention a multiple gun assembly has three guns for example, with electrodes nested afiixed in mating indentations about contoured surfaces of a single central ceramic mounting post, which holds each electrode in place and aligns the beams of the guns for proper convergence.

The above features and objectives of the invention are illustrated and described in detail in connection With the embodiment shown in the accompanying drawing, where- 1n:

FIGURE 1 is a front elevation view of an assembled three-beam electron gun constructed in accordance with the invention;

FIGURE 2 is a plan view in section taken through lines 22 of FIGURE 1; and

FIGURE 3 is a perspective view of the central mounting post for the gun assembly.

Referring now to the drawing, three gun assemblies are arranged about the outer surface of a central contoured mounting post to provide three beams converging along axial lines 11, 12, 13 down the center of the respective guns. The mounting post 10 is preferably a ceramic such as steatit-e or ia lumanae, which is metallized at a plurality of mating indentations 15, etc., by application of a liquid suspension powdered molybdenum base which I is sintered by firing at about 1800 C. in a hydrogen atmosphere furnace, and which base is then nickel plated. This provides a surface 17 onto which the electrodes may be brazed, such as shown by cathodes 16, 16' and ice 16" of FIGURE 2. In the case of the cathodes or other electrodes which should be maintained at equi-potential, the straps 18 are welded between at least two pairs of the respective electrodes of the three guns.

By nesting the electrodes in mating indentations 15 and affixing them in place the dimensional tolerances are fixed at assembly and maintained throughout operation, and there is no possibility during assembly of disturbing the positioning of the electrodes.

Thus, it may be seen in FIGURE 3 that each of the series of electrodes in turn are assembled in the gun in the associated mating indentations of the center post 10. Since the cathode 16, control grid 18, screen grid 20, focus electrode 22, accelerating anode 24 and convergence electrode 26 are all of different dimensions and are spaced on the center post 10 at different positions, the

assembly process cannot become confused and a simple jig will hold the electrodes in place for brazing to the mating metallized ceramic indentations.

Accordingly, it is seen that the present invention has provided an improved assembly for multiple-guns which affords uniformity and preciseness not possible in prior art devices and assembly methods. Accordingly, those features of novelty definitive of the nature of the invention are defined with particularity in the appended claims.

What is claimed is 1. A multiple-beam electron gun assembly comprising in combination, a contoured longitudinally disposed central mounting post having mating indentations for receiving a plurality of electrodes in each of at least three electron guns aligned axially in three longitudinal arrays distributed about its outer surface, and a set of cylindrical electrodes for each of said guns aflixedalong only a segmental portion to said outer surface in said mating indentations.

2. The assembly defined in claim 1 wherein the post is ceramic with a fired metallized bond at said matingindentations to which said electrodes are brazed.

3. The combination of a plurality of electron guns for a single cathode ray tube, each having a plurality of separate cylindrical electrodes aligned to form a single beam, and a mounting array to hold the guns in spaced relationship comprising a central mounting post wholly within the region between the three guns and having indentations on its outer surface to receive in a mating position the electrodes of each of said guns in an axial array along the mounting post.

4. The combination as defined in claim 3 wherein the mounting post is tapered to provide convergence of th beams of said guns.

5. In an electron gun assembly for a three beam cath ode ray color tube wherein each gun has a series of axially aligned cylindrical beam processing electrodes, a tapered ceramic mounting post with a triangular cross section presenting three contoured outer surfaces adapted for resting centrally between the guns for nesting a plurality of electrodes for each of the three respective guns in final position to receive the inner portion of the electrodes of each gun in contact on one surface to define by the degree of taper of said post a predetermined convergence angle between the three beams.

6. An electron gun assembly as defined in claim 5 wherein the contoured surfaces have aflixed thereon a metallic film and the electrodes are brazed to said film.

7. In a three gun assembly having therein a series 3 4 of individual electrodes axially aligned for each gun, with References Cited by the Examiner the respective guns positioned to define three heams con- UNITED STATES PATENTS verged for use in a cathode ray color tube, a slngle longrtudinal insulating post located in the region centered be 2735O31 2/1956 Woodbndge 313 70 tween and substantially along the entire length of the three 5 3,128,407 4/1964 313-268 X guns with three surfaces facing the respective guns being 3,164,737 1/1965 Messmeo et 313 '69 contoured to receive the electrodes in nested positions I N HU KERT P E thereon, and having the electrodes of each gun affixed OH C "mary f to a corresponding one of said surfaces. 7 POLISSACK, Asslstlml r- 

1. A MULTIPLE-BEAM ELECTRON GUN ASSEMBLY COMPRISING IN COMBINATION, A CONTOURED LONGITUDINALLY DISPOSED CENTRAL MOUNTING POST HAVING MATING INDENTATIONS FOR RECEIVING A PLURALITY OF ELECTRODES IN EACH OF AT LEAST THREE ELECTRON GUNS ALIGNED AXIALLY IN THREE LONGITUDINAL ARRAYS DISTRIBUTED ABOUT ITS OUTER SURFACE, AND A SET OF CYLINDRICAL ELECTRODES FOR EACH OF SAID GUNS AFFIXED ALONG ONLY A SEGMENTAL PORTION TO SAID OUTER SURFACE IN SAID MATING IDENTIFICATIONS. 